1. Fields of the Invention
The present invention relates to a motor control apparatus, and more particularly to a motor operating with a microprocessor for selectively executing two different output modes: an electric generator mode or a power machine mode of the motor and the motor is applied in various different fitness equipments such as a weight lifting machine and a rowing exercise machine for stretching exercises and thus simplifying the components of the fitness machine.
2. Description of the Related Art
As we all know, a traditional weight lifting machine (not shown in the figure) usually uses metal weights as the source of exercise resistance, and the weight lifting machine comes with complicated components and large volume that result in wasting spaces and generating noises. Therefore, manufacturers try to replace the metal weights or flywheels with a motor operated in an electric machine output mode and provide an exercise resistance to various different fitness equipments such as the fitness machines with a design of an electric motor as disclosed in U.S. Pat. Nos. 6,790,163, 5,762,584 and 5,435,798, so as to provide the expected exercise resistance. Thereafter, a built-in program of a microprocessor is operated together with the motion of a force measuring device for the clockwise and counterclockwise rotations of a motor of the electric machine in order to provide a resistance and rewinding function as disclosed in R.O.C. Pat. No. I268789 entitled “Programmable control resistance apparatus and method used for fitness equipment”.
Although R.O.C. Pat. No. I268789 can achieve the expected effect, any person with ordinary skill in the electric field knows about that when the axle of an electric machine is braked in a reverse direction, the electric machine will have a “plugging” phenomenon. In other words, the electric machine will produce several generated current feedbacks to the overall circuit system, such that if the generated current is not eliminated properly, then the life expectancy of the motor and the overall circuit system will be affected adversely.
Further, the aforementioned patent uses a force measuring device to measure the data of a force exerted onto a rope, and the detected data is compared with a predetermined value of the microprocessor to control the clockwise and counterclockwise rotation of the motor, or even provide an appropriate safety response based on the existence of an abnormal force exerted onto the rope. In fact, the force measuring device usually has to go through a “stable” process each time when a user sets the unit measuring time (which is similar to a fluctuation of the readings at an early stage of a measurement occurred when we stand on a scale to measure our body weight), and thus we can obtain the best measured reading, but such arrangement greatly slows down the response of the overall circuit system. Simply speaking, the conventional resistance control apparatus is unable to cope with the natural response speed of a general exerciser's brain and limbs, unless the exerciser is operating and exercising at a very slow constant speed.